Several types of infant seats are already existing which in order to securely fasten the child to the seat comprise a strapping being formed by two adjustable straps being linked through a buckle to a crotch strip, said straps being joined to each other at the rear portion of the backrest and thereby forming a length passing through a tension device and extending beyond the front portion of the seat.
For the children's safety these seats are generally installed on the back seats of the motor vehicles.
Some of these infant seats comprise a backrest being provided with a headrest and are designed for rather small children of 1 to 5 years of age, for example.
In some of said seats the headrest forms a separate piece that is to be fitted to the backrest in an upwardly shiftable arrangement in order to be thus adapted to the child's height, the two straps of the strapping being fitted to the headrest.
In these seats there is the drawback that the straps will progressively adapt to the child's height as per the extent of the child's growth, but the same does not happen with the crotch strip, this latter being fixedly secured to the seat, in such a way that the more the child grows the greater its discomfort on the seat becomes because of the increasingly stronger pressing action being exerted on its crotch by the aforementioned strip.